Thanks to the wide spread of digital devices such as a mobile phone with which a person communicates with another person while looking at the opposite person's face, a webcam used for video chatting and a digital camera with which a person's face can be shot, users who want to photograph and edit portrait images in their daily lives are dramatically increasing.
In respect of this, a portrait image editing method which triggers the users' interest by replacing a background region exclusive of a character region on a portrait image with a different interesting background has been introduced. To perform the aforementioned method for editing the portrait image, a technology for distinguishing between the character region and the background region included in the portrait image is essentially required. A graph cut algorithm may be an example of the technology. The graph cut algorithm is a technology for distinguishing different objects in an image based on an initial value(s) granted to a region(s) of the image and it may be usefully used to distinguish between a foreground region (i.e., a character region) and a background in the image.
As a conventional technology for setting the initial value of the graph cut, a technology for setting the initial value by a user's manual input may be considered. However, according to the technology, the user has to directly set a part corresponding to a character region for each portrait image which the user wants to edit. For the reason, this causes inconvenience due to the user's too much input. Furthermore, as another conventional technology for setting the initial value of the graph cut, a technology for using a numerical model such as a Gaussian mixture model (GMM) may be considered. However, according to this, it requires an excessively large amount of calculations so that it may cause slow calculation speed. Therefore, it may be inappropriate to run on a mobile terminal which cannot have a very high performance processor.
Accordingly, what is needed is a technology for effectively setting the initial value of the graph cut to accurately provide a service of editing a portrait image on the mobile terminals.